In prior art, devices for providing a heat source or fire (such as gas stoves, furnaces and electric stoves . . . ) are controlled by a knob, to adjust the strength of the heat source or the strength of the fire. However, the devices for providing a heat source or fire only display the strength of the heat source or the strength of the fire on panels on where the knobs are disposed, users at a distance are unable to know the strength of the heat source or the strength of the fire, hence, the users must come closer to the devices for providing a heat source or fire to know the strength of the heat source or the strength of the fire on the panels. It is not convenient to the users who want to know the strength of the heat source or the strength of the fire at a distance.
Consequently, there is a need to solve the above-mentioned problem that the user can't know the strength of the heat source or the strength of the fire at a distance.